1. Field of the Invention
The present invention relates to an inorganic composite material which is suitable for many applications such as electronic and structural materials, and to a method for producing the composite material.
2. Description of the Prior Art
Various materials with properties appropriate for their particular applications are required in the manufacture of electronic components, structural parts and other products, and composite materials combining the characteristics of two or more substances are often used in order to obtained the required properties. For example, those such as resin-ceramic and metal-ceramic composite materials are widely used. However, the aforesaid resin-ceramic composite materials have the disadvantage of low rigidity. On the other hand, metal-ceramic composite materials have, for example, the form of metal grains 101 dispersed in a ceramic matrix 102, as shown in FIG. 7. The proportion of ceramic constituents in such materials is large, and the metal grains only occupy at most about 50% by volume. The ceramic properties and metallic properties of such composite materials are only manifested to an extent corresponding to the proportions of ceramic material and metal, respectively, which are contained in the mixture. Furthermore, although the rigidity of such composite materials is relatively high, the distances between the grains dispersed in the ceramic matrix is large, and consequently the mechanical strength of such composites is extremely low. Moreover, triangular regions 103 (i.e., regions in the cross-section bounded by at least three grains; triple point of grain boundaries) occupy a relatively large area in articles formed from such composite materials, and numerous pores are present in these triangular regions. Corrosion may begin from these triangular regions, and consequently cracks may occur. Hence, such composite materials tend to exhibit poor weather resistance and low mechanical strength.
In addition to the above-described dispersed type of composite material, for example, multilayer laminated structures composed of thin metal films and thin ceramic films are well known as composite materials applicable to the fabrication of magnetic cores. However, if the relative density of 95% is provided to raise the mechanical strength of such a composite material, then plastic deformation will destroy the laminated structure, and consequently, as in the case of the above-mentioned dispersed type of composite material, both the ceramic properties and metallic properties are only manifested to an extent corresponding with the proportions of ceramics and metal, respectively, contained in the material. For example, no material developed so far has the sufficient magnetic properties of magnetic metals, while at the same time adequately exhibiting the electrical insulation properties associated with ceramics.